My 1991 Grand Wagoneer is suddenly seeming to go through gas, oil and coolant way too fast, what could it be?


Asked by Nov 04, 2012 at 06:59 PM about the 1991 Jeep Grand Wagoneer 4 Dr STD 4WD SUV

Question type: Maintenance & Repair

I bought my 1991 Grand Wagoneer a few months ago for $6,000 and she has 133,000 miles on her, and I'm in
Northern California. I had a new radiator and thermostat put in and fixed some oil leaks, only to reveal a main seal
oil leak, that the mechanic said he coudn't fix himself. He didn't charge me or the work, and said that I'd be fine for
6-12 months and then have a specialist drop the engine. Ever since then, I seem to be overheating more, using lots
of gas, approx. a tank for only about 150 miles or so (haven't gotten an exact count yet), putting in about 1 quart of
oil a week, and topping off the coolant every few days. A whispy smoke comes out of where I put in the oil when I
take the cap off. And the idling seems to have progressively gotten rougher to the point that I'm stalling if I have to
idle at a light for too long. I'm hoping for simple fixes, but is it time to rebuild/replace the engine? :(

I knew eventually work would be required, but not this soon! She looks great at least!

Thanks so much for any help!

19 Answers


what did your mechanic replace? and as for the rear main seal, it is a simple job, it 2 pieces and doesn't require you to take motor or trans out. all you have to do is remove oil pan, then remove rear main bearing cap and the bottom of the seal will be in your hand, top part you have to push out, sometimes difficult. as for the overheating, do you see lots of white smoke come out the exhaust? check your oil, does it look like chocolate milk? if yes you probably have a blown head gasket from repeated overheating. most of these overheated due to plugged radiators or bad clutch fans. as for such bad fuel economy and oil use, did your mechanic have the intake manifold off? I love my past 9 grand wagoneers.

2 out of 2 people think this is helpful.

Thank you so much for your help! Wow, 9 Grand Wagoneers! The one in your photo is a beauty! I am having a hard time locating my receipt with what exactly the mechanic did, but will add that info when I find it, so I don't recall if the intake manifold was off. But I wanted to mention that my biggest problem since I wrote the question, is the stalling. It has gotten so much worse, I can barely get anywhere if I have to stop at a light, without stalling and having to restart. And even slight hills are a problem to get up at speed. That is good news about the main seal, they made it sound like a really difficult job. I guess that seems to be the least of my problems now! The oil that leaks out is a dark brown when I put my finger in it on my driveway, but my driveway is black asphalt, so hard to say if it is milky too. It looks more like balsamic vinegar to me. And my dip stick barely ever has enough oil on it to see... it's really twisted and hard to use. I only see lots of white smoke when starting up the truck cold, I haven't noticed any while driving. The blown head gasket sounds pretty likely now. That happened to a previous car of mine (Honda Civic), and I remember replacing the radiator only to find the blown head gasket was the real problem. Could this have anything to do with the stalling? And going through so much coolant? How much should something like this cost? Am I making things worse by still driving, is this going to get to the point that I am stuck somewhere needing a tow to get to a garage? Thank you again for your continued help! Katie P.S. This is mine, Maggie the Waggie :)The oil marks on the driveway are far worse now though!

1 out of 1 people think this is helpful.

Found the receipt! Here are the details, thanks again! The formatting won't let me write a list, sorry for the run on sentence! dated 9/19/12 - replaced : radiator, lower radiator hose, intake gasket, oil pan gasket, P.S. pressure line, r&r valve cover gasket, thermostat, fuel hose, P.S. return hose. All they charged me for was the radiator, hose and p.s. pressure line. The rest they didn't charge me for because of the newly discovered rear main oil seal leak. Seems like a good honest shop, but they don't really want to see my car again, they opened up a can of worms that they weren't expecting and don't want to deal with. Thanks for any ideas!


Don't know if it matters at all, but I lose power steering when I stall at stop signs/lights as well. I even just stalled driving down a hill not braking, but not gassing it either, I guess the idle speed just got too low? On the coolant issue, looks like the radiator cap is old, even though we had the new radiator put in. Should I replace that in high hopes that it could solve the coolant issue?

1 out of 1 people think this is helpful.

OK, new intake gaskets, so the intake was off exactly as i had suspected!! I specifically asked due to the symptoms. Reason, most cars haven't had carburetors since the mid 80's so roughly 25 years ago and I dont care who you bring your car to, they simply don't know how to work on it. These grand wagoneers where the last car to have a carb on it aside from a few weird Suzuki and random odd Hondas. Late model carburated cars can be a nightmare with vacuum hoses and emissions devices as they had a very hard time passing emissions. There is literately hundreds of feet of vacuum hoses and emissions tubing under the hood, and lots of plastic connectors and plastic sensors (mainly thermo type vacuum) and being that age, and a VERY common problem anyway, all those rubber hoses are old, dry rotted and brittle. I can guarantee once you touch them (you have to remove all them to do the intake gaskets) they break, start leaking as in air vacuum leak, or are not hooked up correctly as most of the hundreds of feet of hose are the same size and all can plug into each other but it all has to be hooked up in an exact way. If your mechanic said he isnt capable of doing the rear main seal, he defiantly was far from capable of doing intake gaskets. I am sure they replaced the oil pan gasket thinking that was the oil leak but it was rear main seal instead, it is hard to tell as they leak from a very close area that isn't visible. Next, the distributor was most likely removed, once removed, the timing has to be reset, and these have to be exact, we are talking in a 360 degree rotation, it has to be within about 5 degrees of what is specified, dont remember what is it that year, but like 12 BTDC, mechanic knows what that means. Next, the carb. There should be carb, then gasket, then plastic spacer, then gasket, then intake. Those spacers are plastic mounted to a very hot engine, if they are not broke when removed, they crack when re-installed when tightening and again, more vacuum leaks. I seen some people just leave the spacer out, don't because it wont work, causes the gas in the carb to heat up so much that the gas boils, thats the reason the spacers are there. Carbs are adjustable. 2 hidden screws at bottom facing forward on each side adjust idle air fuel mixture, if screwing 1 out/in doesnt make much difference, but the other 1 does, the carb is probably dirty inside and needs to be rebuilt. Then there is an idle speed screw on the throttle linkage, also a idle speed solenoid that should be check to see if it is plugged in correct because it has same plug in as air conditioning compressor and i have seen people swap those before after replacing intake. Need to make sure the carb choke is plugged in both electrically and with the small metal tubes from the exhaust in intake manifold. Choke is adjustable, start closed when cold and open when warmed up. Next, do you see any coolant on the ground? steam from engine bay? When you say overheats, how often, how long do you have to drive it before it overheats, does it matter if your sitting at a stop of driving down the road? Dont drive it if the temp gauge goes into the red. Do you only have to add coolant after overaheating, that would be normal as overheating will push coolant out of the engine. You also said fuel mileage is bad, well they always were, 10mpg in town and 12 on the highway, if all is running perfect.

3 out of 3 people think this is helpful.

This is so helpful!!!! Thank you! I do not have a Jeep specialist close to where I live, so these suggestions will really help me with the new mechanic (friends have recommended a new shop). Even though some things may be the previous shop's fault, I don't think I should take it back to them after what you have said. A lot of it makes perfect sense, and hopefully it isn't as bad as a blown head gasket. First off, just wanted to mention that my A/C doesn't work, I bought the truck knowing this, don't know if it matters, but you mentioned the compressor so I thought I should say something. It is not just in need of a recharge, something major (compressor?) needs to be replaced, I figured I could worry about this later though. To answer your questions : I often see coolant on the ground, but haven't figured out if it is only when overheating or all of the time. The truck overheats after driving for about half an hour or so (it doesn't matter if it is continuous driving or stop and go around town, idling or turning on and off the engine at different errands), I haven't let the temp gauge go over about 220, not really close to the red, what is the normal operating temp for these Jeeps? I put in coolant about every other time I drive, maybe about 1/2 a bottle. I will preemptively put in coolant if I see that the temp seems to be rising faster than normal. Which minimizes the overheating, usually just some steam once I park rather than a complete overflowing of coolant everywhere. The coolant reservoir is consistently practically empty everytime I look at it, on a warm or cold engine. I go through coolant like crazy filling it as often as I am, but so far have made it home or to where I was going before a major overheating. Then I just wait to fill it up before I drive again. I noticed that the silver "paint" on what I think is the entire engine, is all bubbly, and I can push down the bubbles with my finger. Looks like extreme heat caused it, is this normal, no mechanic has mentioned it though. As for the fuel mileage, I meant it's even worse than it was, I was getting 10 and 12, but now seems a little worse, the gauge seems to drop dramatically once it hits around the 1/2 tank mark, it will jump from 1/2 tank to close to empty and back up again sometimes, is this just how the older gauges work? Speaking of gauges, the oil gauge goes up and down too, in the middle while I drive, and drops all the way down when I stop at a light. Another point, sorry I didn't mention this before incase it matters, I have some oil in the air cleaner housing, and the large opening on the left (where people often have a hose connected, I do not) sometimes is smoking. You are doing such a great thing by helping so much on here!! (I attached a photo of my engine, just in case it helps at all, you can't really see much though!)

1 out of 1 people think this is helpful.

Hi there, the a/c system has nothing to do with the car when it is not running so you can excuse any question to that. A/C parts are getting hard to find for these. So you have a coolant leak, first thing is to bring it to a mechanic and they can pressure the cooling system and find the leak because you should never have to add coolant, it should be a completely sealed system minus the overflow bottle. The overflow bottle should only have about 2 inches of coolant in it, don't fill it up. Next, 220 is not overheating and 30 min into a drive, it can reach those temps, that is normal for a hot climate. First, a thermostat opens and closes allowing the coolant through the radiator. Stock thermostat opens at 195 degrees so the car has to run atleast that hot. You can get thermostats that open at 180 or even cooler at 160. It is a great idea to run a cooler therm. if you are in a warm climate where you dont need a lot of heat from the interior heater. Next, once the therm. opens and allows coolant to flow through radiator, the coolant cools down and then back into the engine. The fan on the front of the motor draws air through the radiator to cool the coolant even more. Although the fan turns all the time, it is on a clutch so it really isnt spinning that fast. Once the engine runs about 225-230, the clutch for the fan on the front of the motor will fully engage pulling a lot of air through the radiator to keep the engine cool. a car isnt really overheating until it reaches about 250 which is why the clutch fan is fully engaged at 225. So a mechanic should check to make sure the clutch fan is working. Also, these jeep will run on the hot side if the fan shroud is damaged or missing. Since your radiator was just replaced, they probably didn't put the fan shroud back on as they are typically cracked and fall apart when touched because they are made of plastic and are subjected to a lot of heat. Things to help keep the engine cooler. First install a cooler therm as listed above. Next, typical coolant water mix is 50/50 but if you live in a climate above 30 degrees, you can put in 90% water and only 10% coolant as water is much better at heat dispensation. And once you fix your leak, I would also recommend a product called water wetter, I have used it before and it works well with the 90/10 mix. If your in a colder climate, you need to run 50/50 mix and the water wetter wont work. Next, the engines on these are not painted silver from the factory and if you paint the engine, they take special high temp paint. So someone has been doing some painting. And also, many chemicals used to clean the engine will cause that also. Next, oil gauge, they are really inaccurate on these (as are most of the gauges), they should run typically in the middle when driving, and most only have about 5psi at idle around 800rpms so that is really close to the bottom of the gauge. You should have the oil pressure checked at a mechanic with a mechanical gauge to see what pressure it really has and that shouldn't cost more than $50 to check. Next with the oil in the air cleaner, you should not have oil in the air cleaner, clean it all out, change the oil cap which is also the breather for the engine as there is a filter inside, and change the pcv valve. With a high mileage engine as you have, you may get a light oil residue build up inside the air cleaner, but you should not have oil pooling in there. If you do have oil pooling in the air cleaner after cleaning it out within 500 miles, your engine has excessive blow by. It is not the end of the world, will not cause a running problem, but it does mean that the engine is worn. And with the gas gauge, again very inaccurate and a big big problem on these. The sender in the tank goes bad or it has a bad electrical ground. DONT take the gas tank out to change the sender as most people and even seasoned mechanics do. There is an access plate under the rear seat carpet to change the fuel sending unit. As with the fuel mileage, you say the engine dies out, so it definitely is not running correctly which is leading to a decrease in fuel mileage. And something that just popped into my head, with your low oil pressure, you should bring the truck to a competent mechanic before you do any more driving. The truck may be running bad because it is running way to rich which mean a lot more gas is going into the engine than what should be. This extra gas will end up in the engine oil which makes the oil much thinner than it should be, causing low oil pressure and also gas has no lubricating properties so the gas in the oil WILL cause engine damage. The thinning of the oil can also cause the excessive blow by (oil in your air cleaner). Now as discussed earlier, if you do find out you have to much blow by, you can run 20w-50 engine oil if you are in a climate that is above 30-40 degress, if your in an area that is colder, then run 15w-40. This will slow down oil blow by (also know as oil consumption) but will not really slow down a leak. So my advise, bring it to a GOOD mechanic, first find the coolant leak, dont fix it yet, then check the running problem, dont fix it yet, then check the oil pressure, if low, change the oil and put regular 10w-30 in it. If oil pressure is still low, your probably going to need an engine soon so stop spending money on it. If oil pressure is ok, 5-8psi at 800 rpms is ok, and 30-40 psi at 2500rpms. If oil pressure is ok, then fix the coolant leak, running problem, and oil leak you previously listed you had. With those problem solved, I believe you will be happy. Even if you have to much blow by, you can still drive it that way.

4 out of 4 people think this is helpful.

Thank you so much for your extensive knowledge! I think I may have found a good mechanic. This mechanic has confirmed a lot of what you have said, and did a full diagnostic and found some of the other things you said to be true too. The previous mechanic DID put a majority of the vacuum lines on incorrectly after they replaced the intake manifold, just like you said, and that is causing the poor running and stalling. Luckily the previous mechanic will pay for a majority of the cost - around $280 (approx. 2 hrs labor and $50 parts) - for my current mechanic to do the vacuum lines correctly. I already feel more comfortable with this mechanic, they stressed how exact the vacuum line placement needs to be and they have a diagram to follow for the wagoneer, just like you said. So as for the coolant leak, the main lower radiator hose wasn't screwed on tight enough, and that has helped with the temp a lot, but they also said that it is leaking in the timing change cover (I think) and that when I fix that, then I should also do the chain as well while they're in there, do you agree? There was no cover over the fan when I bought the car, do you suggest I get one put on? Thank you for the therm suggestion, I'll try and find out what my new one opens up at. It doesn't get too cold where I live, every once in awhile it will dip below 30 at night in the winter, but we don't get snow or anything, I'm just a bit north of San Francisco, CA. Regarding the oil pressure, mine reads almost exactly as you described, I didn't even know that it is supposed to go down when idling and up when driving, so that's good. This mechanic also suggests the pcv valve be changed to help with the oil in the air cleaner. I guess I have a leak in my oil pump AND the rear main seal, both needing to be replaced. Another thing that made me feel good about this mechanic is that they said removing the entire engine to replace a main seal is ridiculous and they do it the way you said to. It should be approx. $715 for that (approx. 6 hrs labor and only a $20 part). The two other mechanics I've talked to said that they had to remove the whole engine! To fix everything they are quoting around $2,000 total. Does this sound reasonable? I'm going to have them do the vacuum lines first, and then save up some money and do the rest, if you think I can wait. They claim that once I do all of this stuff, then she'll be running great and then just normal maintenance will be needed. I'm not going to worry about the gas gauge, I'll just try to keep the tank full. I will take your advice re: coolant mixture and oil type. I have been using synthetic high mileage Mobil 1 10-30. Re: the engine painted silver... I'll ask the mechanic what that is, it just doesn't look right to me. I'm just hoping that after all this I will have a reliable car that I can take on road trips and up hills, and maybe even tow a small camper someday! Your help and tips have really helped!!!


Hi there again. Glad to see you found a good mechanic. As for the timing chain front cover, yes, you should have the chain and 2 gears replaced when they take the cover off to fix the gasket. Chains stretch out and the gears it rides on wear down with mileage. Timing chain and gears are just like on a bicycle, and they spin around 2500 times ever minute while driving 65mph so you can imagine how many times they have been around!! And if it was mine, I would replace the water pump at same time because is will be removed to do the timing cover gasket so the only thing you have to pay for is the part, no extra labor. I have had to replace the water pump on every single GW I have had, as they have a rubber seal that has to be water tight, and your Jeep is 23 yrs old. As for the oil leaks, the oil pump is actually inside the front timing chain cover so I would recommend a new oil pump as well, they will fix that at the same time as the gasket and chains since it will be already disassembled and the only thing you have to pay for would be the extra parts again which are not much money. The oil pump is 2 gears and also spin together several thousand times a minute just like the timing chain and gears, so with mileage, they do wear also. We own a repair shop here near chicago IL and i am a vivid jeep fan so if you wanna know where my knowledge came from, there it is. $715 is steep for just rear main seal. Chilton labor guide gives 4.2hrs to change rear main seal x $85 per hrs is our rate = $357 , plus parts: 5 quarts oil, rear main seal, oil pan gasket, parts under $100 so that is only $457. I imagine for 6 hrs he is doing more, maybe including fixing the vacuum hoses too or checking the bearings since the oil pan is off. With your climate, I would recommend a 20% antifreeze 80% water mixture. This will protect you down to 20 degrees which will be safe for you. Some mechanics will say that the mix will boil to soon as water boils at 212 and your engine may run hotter that that, but what most mechanics dont know is that water under pressure (cooling systems are pressurized for this reason), wont boil till about 240, and that is just the properties of a pure 100% water with no coolant added. SO with that 20-80 mix, you wont have to worry about boil over either. Get it running good, change the oil with regular 10-30 and change pcv valve first before you check for blow by or use thicker oil. I agree with the mechanic, once fixed, you will enjoy it. Keep it full of oil and getting the vacuum lines fixed so you can save up is the best plan, then you will be able to drive it and enjoy it in the mean time. OK, pricing, rear main seal estimate $450 ($100 for parts and $350 for labor) includes labor, oil pan gasket, rear main seal, and 5 quarts oil. Timing cover job estimate (you have to change oil again as coolant runs into the oil pan) $675 ($400 in labor and $275 in parts) includes labor, new timing cover gasket set, new oil pump kit, new water pump, the chain and both timing gears. Sometimes the entire timing cover needs to be replaced also so that would add to price. They are aluminum and it houses the oil pump so it is under a lot of stress. So timing rear main seal and timing cover job should be around $1100-1200, now add some in for doing all the vacuum hoses, say $200-300, set ignition timing another $50-100, so I would say really around $1600 but they could be doing some extra things not fully explained to you either. Some great sources of parts weather needed or not, I find interesting to look thru: and also specializes in parts just for 1963-1991 FSJ grand wagoneers.

4 out of 4 people think this is helpful.

Ohh, and your fan shroud, yes, you do NEED to get one, it will drastically improve cooling system performance.

1 out of 1 people think this is helpful.

Thank you! Thank you! I decided to just go for it and do everything at once. It's a lot of money, but the mechanic seems to think she'll be running in tip top shape once all this is done. You're right, they're doing a lot more than I listed, I mentioned a few of the things that you said to my mechanic and they are also changing those things out as well, such as the gears the timing chain is on. I'm waiting to hear back about the water pump, he said $97 for the part, no extra labor, if I do need to replace. He'll let me know if it has been replaced or not. I'm not surprised if things are a little more expensive here in Northern California, it seems like everything is! I'll do the fan shroud soon, maybe even myself? I love! Already have gotten a few things from them. I feel like there are a million other little things to do, but I feel so good about getting all of this engine work done right now. Thank you again, you have really helped me understand how things work and why certain things are necessary, next I need to read my Haynes manual!


So it has been awhile since your Jeep was all fixed up, how is she running now?

1 out of 1 people think this is helpful.

I've been meaning to update you! Just didn't even know where to begin with everything I ended up having done... First off, she's running like a top! I had them do everything that they recommended. ($2,200 later...) The oil leak ended up being from the intake manifold gasket, so they replaced that. They re-routed the vacuum lines, and replaced the related parts, like the PCV valve. I was leaking coolant from the timing cover, so they replaced that, they were having a hard time finding the part so I purchased it myself from I had them replace the timing chain, gears and the water pump at the same time, just because they were in there. My oil pump was leaking too, so they rebuilt that. So after all that she's running really good. BUT turns out that my number 5 cylinder has low compression, I can barely notice it, but I guess this is the beginning of the *hopefully* very slow death of this engine? I still leak a little oil, they said it is the blow by because of the cylinder and can't really be fixed. It's fine though, and pretty minimal. Secondly, my smog pump pulley was frozen so they took the belt off and basically said it would be around $300 to have that replaced before the next time I have to have her smogged (about a year from now). My gas mileage is still horrible, approx. 8 mpg on average! Any ideas to help that would be appreciated :) At least I have figured out that my gas light goes on when I have about 4 gallons of gas left, which isn't good that I know because I really push it now. I still need to put a cover on my fan, but with my new radiator, she runs really cool now. Thanks for checking in, and any further tips are ALWAYS welcome!

I was reading this email string and I have 90 grand wagoner and was curios if Kurt could reply about his shop address in Chicago. I live in indianapolis and would drive it up there for some repairs. Mine is in solid shape but I need to take it to another level.


you can find us at !!

1 out of 1 people think this is helpful.

This was a great thread Kurt and Katie. I just blew a head gasket last night and I'm gonna bring my chief to repair in the morning. These two fsjs are my dream cars. Dan

Kurt, can you recommend a wagoneer or cherokee chief mechanic in the chicago or chicago suburb area? Thanks Dan


your bad gas milage could be worn cam i had worn cam in my 77 and was getting 10 - 12 after i replaced cam

Awesome thread Katie and Kurt! I've spent endless hours online searching for concise troubleshooting and repair info for my jeep, and the only. thing I've got to show for the effort is a chronic case of Computer Generated Narcolepsy. However, it was refreshing to run into such an intelligent and informative thread. Fantastic questions Katie! And Kurt, your responses well explained and easy on the ears, thankfully lacking in the arrogance and $9 words that I see so much of from those forum guys that always have the huge egos and wrong answers. Thanks to you both! BTW, mine is an 87 Cherokee - but I still read it and still found it to be well worth reading,

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